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5 But to Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell.
'To open,' as in Revelation 9, signifies communication and conjunction.
(References: Apocalypse Explained 537)
11 The angel of Yahweh said to her, "Behold, you are with child, and will bear a son. You shall call his name Ishmael, because Yahweh has heard your affliction.